1. Field of the Invention
This invention relates to a hinge and an image input/output apparatus using the hinge.
2. Related Art
A multifunction processing machine including a printer and an image scanner as an image reader in one piece is known as an image input/output apparatus. Known among such multifunction processing machines is a machine having a scanner housing for housing an image scanner as an open/closed body and a printer housing for housing a printer as a main body, both the scanner housing and the printer housing being swingably joined on a hinge.
However, with the multifunction processing machine including the scanner housing and the printer housing swingably joined, the scanner housing for housing the image scanner is heavy and there is a danger that the scanner housing may rapidly drop in a closed direction under its own weight and a user's finger may be caught in. Thus, a hinge including a brake mechanism is used to join a scanner housing and a printer housing in a related art (for example, refer to Japanese Patent Publication No. JP-A-2001-98839).
In the related art, a wedge body and an elastic member as urging device are housed in a base part of the hinge and the wedge body is urged toward the side of a rotation body by the elastic member for bringing the slope of the wedge body into sliding contact with a cam part of the rotation body, thereby adding the rotation force to the rotation body in the direction of bringing the scanner housing away from the printer housing, thereby preventing drop of the scanning housing in the closing direction thereof.
FIG. 13 is a drawing to show the hinge 5 in the related art. In the hinge 5, the upper end margin of a fixed-side hinge body 52 is formed as a convex circular arc margin with the shaft hole center as the circular arc center, and a small protrusion. 53 is provided in the circumferential direction of the convex circular arc margin. A moving-side hinge body 54 is formed with a concave circular arc face with the shaft hole center as the circular arc center, and a raised step part 55 is formed on the concave circular arc face. According to the hinge 5, the raised step part 55 mounts the protrusion 53 in the process of closing the moving-side hinge body 54, so that a predetermined frictional force can be produced between the raised step part 55 and the protrusion 53. The hinge 5 uses the frictional force to brake pivotal movement of closing the open/closed body. Therefore, the hinge 5 can prevent rapid drop in the closing process of the heavy open/closed body.
However, since the protrusion 53 and the raised step part 55 are brought into sliding contact with each other, the moving-side hinge body 54 needs to be provided with a portion 51 covering the upper end margin of the fixed-side hinge body 52, as shown in FIG. 13. Further, the portion 51 covering the outer peripheral margin receives a strong force from the protrusion 53 and therefore must be made large so as to provide strength. Thus, the hinge 5 involves a problem of enlarging its shape accordingly.
The hinge 5 also involves a problem of more enlarging its shape if the open/closed body becomes heavier. Specifically, if the open/closed body becomes heavier, a larger frictional force becomes necessary. In the hinge 5, if an attempt is made to increase only the frictional force without changing the size of the hinge, degradation of the protrusion 53 is promoted due to wear. Thus, to brake the heavier open/closed body, it is necessary to lengthen the distance between the protrusion 53 and the shaft hole center so as to provide larger moment in the opening direction without changing the magnitude of the frictional force. Therefore, the shape must be enlarged. The expression “moment in the opening direction” mentioned here is used to mean the rotation force acting in the direction of bringing the scanner housing away from the printer housing.
Further, if the rotation force is added to the rotation body, a rotation force in the opposite direction to the rotation body is added to the wedge body by the reaction force. Accordingly, the rotation force in the opposite direction to the rotation body is added to the base part, which cannot resist the weight of the image scanner and is broken or warped; this is a problem. Thus, in the related art, a fix member is used to reinforce the base part, for example.
FIG. 14 is a schematic drawing to show an example of a reinforcement structure of a base part in a related art. As shown in the figure, in the related art, an L-shaped metal sheet 62 as a fix member is attached to a printer housing 61. The bottom of the L-shaped metal sheet 62 is fixed to the bottom of the printer housing 61 with a plurality of screws, etc., and an opposite portion of the L-shaped metal sheet 62 is fixed to the ceiling of the printer housing 61 with a plurality of screws, etc. To reinforce a base part 63, the base part 63 is fixed to the L-shaped metal sheet 62 with a plurality of screws, etc.
However, since the fix member to reinforce the base part 63 in the reinforcement structure in the related art, the number of parts is increased and in addition, an attachment step becomes necessary, increasing the manufacturing cost of the multifunction processing machine; this is a problem.
Further, in the multifunction processing machine in the related art, a rotation body 66 is fixed to a side wall and the bottom of a scanner housing 64. Since the side wall and the bottom are contiguous with each other, if the rotation body 66 is fixed to the side wall and the bottom, the weight of the scanner housing 64 concentrates almost on one pole. Thus, in the related art, as shown in the figure, an L-shaped metal sheet 65 as another fix member is provided for the scanner housing 64, thereby reinforcing the side wall and the bottom to which the rotation body 66 is attached; there is also a problem of furthermore increasing the number of parts.